1. Field of the Invention
The present invention relates to a hybrid battery and full charge capacity calculation method thereof.
2. Discussion of Related Art
Generally, a portable electronic device receives a supply of power from a chargeable battery, and a usable time of the portable electronic device depends on the usable time of the battery as the power supply. Therefore, the battery is charged frequently to extend the usable time of the portable electronic device.
To maximize the usable time of the portable electronic device, one known method is to mount two batteries to a portable electronic device. For example, two batteries that have the same size and the same chemical property can be mounted to the same portable electronic device.
However, this method makes the price of the battery increase because not only the circuit used to control the charge and discharge has to be installed to each battery but also the fuel gauge circuit or the micro computer for calculating the remaining capacity of each battery is also provided.
Also, such conventional battery needs extra space because the shape and chemical property of the battery cells that are installed in each battery are typically completely the same, such that there is a problem of reduced energy efficiency per volume.
A quantity (or concept) known as the full charge capacity (FCC) is used as a standard capacity to indicate the accurate remaining capacity (RC) of the battery. In this case, the remaining capacity illustrates the relative state of charge (RSOC) as a percentage of the current full charge capacity. The full charge capacity represents the chargeable maximum capacity of the battery and it gradually becomes smaller as the number of charge and discharge cycles increases. Therefore, the full charge capacity is calculated as the number of charge and discharge cycles increases. According to a conventional calculation method, the full charge capacity is calculated by starting to discharge the battery when the battery is fully charged, and keeping track of the total amount of discharge until the voltage level of the battery reaches an end of discharge voltage level (EDV). Then, the total amount of discharge, which is calculated until very close to the full discharge, is used as the standard capacity to calculate the full charge capacity.
However, according to such conventional method of calculating the full charge capacity, the capacity is calculated at one discharge voltage level prior to the complete discharging, and the remaining capacity is calculated therefrom. Hence, it is difficult to calculate the remaining capacity of the battery when the battery is recharged prior to reaching the full discharge voltage level.